To direct an ejection seat out of a vehicle, it is common practice to guide the seat out of the cockpit with a pair of guide rails. Typically, the seat will have two or three rollers on each side, wherein each set of rollers travels along a single channel in the corresponding rail. Each side of the seat usually having a roller at the bottom, one in the middle and one near the top. As the seat travels up the rails, the seat reaches a point where the top and middle rollers have disengaged from the rail but the bottom rollers are still constrained by the rails. During this interval, the windblast will push the top of the seat aft of the vehicle while the rail constrains the bottom of the vehicle, producing a rotational moment on the seat and causing an undesirable aft pitch angle.
In addition, as the seat emerges from the vehicle, the rails bend due to the force of the windblast on the seat. This causes a further deviation in the pitch angle. One possible way to prevent rail bending would be to add structural support to the rails, but this would add weight and possibly create visual and spatial obstruction.
Thus what is needed, is an ejection seat rail that simultaneously releases the seat rollers and can compensate for any rail bending, such that the rails direct the ejection seat out of the vehicle at a desirable pitch angle.